The present invention refers to a lifting fork adapted to be suspended from a lifting member and which is substantially U-shaped, where the forks make one shank of the U while the other shank, the lifting shank, is adapted to receive a movable attachment means for the lifting member for transmitting a lifting force to the lifting fork.
The lifting member, e.g. a lifting hook of a hoisting crane, can be attached to a loop or the like, which usually is displaceable along the lifting shank of the lifting fork for adjusting the point of action of the lifting member to the centre of gravity of the lifting fork in empty and loaded condition resp. The lifting fork will in this way be self-balancing and the shanks can be kept substantially horizontal in empty as well as in loaded condition, which facilitates the insertion of the shanks under the load and prevents the load from slipping off the shanks.
However, a problem at all lifting forks of this kind known so far is difficulties to withdraw the forks from the load by means of the power from the hoisting crane, especially when the forks are jammed under the load which occurs rather often. The reason for these difficulties is of course that the point of action of the force is located at the lifting shank and not at the forks.